When it is called an unopened bag it is the bag that they were shipped from africa in, Normally a large pillow case or sack.
As far as vet bills go, i do not know one breeder that take CH to the vet. I got in close to 600 last year and only lost 2 that wouldnt feed. When they come in early in the season they have never even done their first shed, which means they havent eaten yet, which means they shouldnt have any enternal parasites unless they were passed from the mother which is unlikley. The majority of parasites are recieved from food that is digested. As far as mites go, They are native to Africa so as long as you are getting the snakes directly from a breeder who only deals with african shipments, you will never see a mite on a ball python in Africa, mites are native to the USA and South and Central America. Ticks are native to Africa however and are found on adult imports and bush babies, i have not seen them before on any CH that i have gotten in, i think the main reason being is beacause they are hatched in captivity and are not wondering around in the jungle.
Also i know that we do and also know alot of importers that have flaygil or panicure (exscuse sp) that they can administor on their own with out paying high vet fees. Like others have said in the past 90% of all CH are just as good as CB. I wouldnt take a CB animal that was eating well and looking fine to a vet, i wouldnt bring a CH either. If the animal eats and eats adn never gains weight or loses weight then maybe a round of panicure, but their is no reason to treat and animal for no reason.
In the past we have always had great luck with CH, actually most of my CH start eating before my CBs do..lol... As long as they are set up properly they thrive.
Thanks
Kim and Matt
N.A.R.C
Sorry so long